The present invention relates to a rotary drill bit comprising a head, at least one roller cutter which is rotatably carried by the head upon bearing means, and a resilient annular sealing means disposed in an annular chamber for sealing the bearing means. The chamber comprises a first sealing surface in the roller cutter and a second sealing surface on the head; at least one of said sealing surfaces being generally V-shaped.
The object of the present invention is to provide a rotary drill bit of the above-mentioned type in which the sealing means is squeezed in the V-shaped sealing surface so that relative movement occurs only at the opposed sealing surface.
Another object of the invention is to provide a rotary rock drill in which the pressure distribution at the sealing surfaces is optimized.
A further object of the invention is to provide a rotary rock drill in which, during drilling, the change in shape of the sealing means is facilitated in direction toward the sealing surface opposed to the V-shaped sealing surface.